Police and protesters clashed in the port city of Alexandria on Sunday after a judge investigating the killing of protesters in Egypt's 2011 uprising said he was transferring the case to another court, a court source and a Reuters witness said.

Lawyers for the plaintiffs wanted the court to consider the report of a fact-finding committee investigating the case against six police officers accused of killing unarmed protesters during the 18-day uprising before proceeding with the defendants' hearings.

Tensions are rising ahead of the second anniversary of the 2011 uprising due on Jan. 25, the date of the first day of the demonstrations, which is expected to trigger protests against new President Mohamed Mursi and his Islamist allies.

After a heated argument with the lawyers, the Alexandria Criminal Court judge adjourned the session and said he was transferring the case to the city's appeals court.

Families watching the proceedings on court television in an adjacent hall erupted in anger and fought with police, who beat them back with batons, the witness said.

"The people want to bring down the regime" and "the people want to cleanse the judiciary," the protesters chanted.

Clashes continued outside the courtroom after the police drove them out.

Police fired tear gas and one police car was shown in video footage ramming into a protester in a scene reminiscent of the violent clashes in 2011.

Two police cars were set on fire, the witness said. Security forces detained some protesters, the state news agency MENA said, and dozens of people were injured.

"The interior ministry has not changed. They are thugs!" chanted the protesters outside the court.

Unidentified assailants raided the court after the clashes and set fire to legal papers and documents inside, MENA said.

After years of upheaval, many Egyptians - from the capital Cairo to smaller towns across the country - feel that discontent could again explode into a new wave of unrest.

The economy has been in tatters since the revolt and many say they have yet to see justice dispensed for the deaths of friends and relatives during the uprising as well as the 16-month rule of the army between the ouster of former leader Hosni Mubarak and the election of Mursi.

Frustration with Mursi is rising, with many saying that nothing has changed since he was elected in last June. Disagreements over a new national constitution late last year triggered violent protests, further eroding trust in his government. (Reporting by Shaimaa Fayed and Abdelrahman Youssef; Editing by Sonya Hepinstall)